Sparking plug



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Oct. 27, 1925- M. SACCHI snnxme PLUG Filgd July 5o. 1924 Patented Oct. 27, 1925.

UNITED STATES PATENT OFFICE.

MICHELANGELO SACCHI, OF TUB-IN, ITALY.

SPARKING PLUG.

Application led July 30,

To all wlw/m. t may concern.:

Be it known that I, MICHELANGELO SACCHI, a citizen of the Kingdom of Italy, residing at Turin, Italy, 38 Corso Valentino, have invented certain new and useful Improvements in Sparking Plugs, of which the following is a full, clear, and exact specification.

My invention relates to ignition devices for internal combustion engines and has for its object to provide improvements in the known sparking plugs in order to make them more inexpensive in use and useful in operation.

The known sparking plugs generally consist of a partially threaded metallic body which is screwed in the engine wall, said body fixedly enclosing an insulating member which usually surrounds or is fitted with a central metallic rod acting as the main electrode of the sparking plug.

Then sparking plugs' are damaged by their insulating member being broken or split, unless they can be repaired there occurs a very considerable waste of material.

My present invention provides for the total conservation of the metallic external body of the sparking plug, which practically does never be damaged, even by usual plugs, and of the central metallic rod, with its terminal binding screw, and allowsa portion only of the insulating member, with one or more electrode-spikes connected thereto, to be changed by very easy operations of screwing and unscrewing.

Said interchangeable members, as a whole, will be termed henceforth the interchangeable ignition plug.

Another object of my invention is to provide a sparking plug which will particularly be adapted to high speed engines, Where very considerable degrees of pressure and high temperatures are reached.

It is known that for these purposes the sparking plugs are required to be well tight, and to have a very efficiently cooled central electrode and porcelains which will not split due to the different action of heat and different expansion coefficients of metallic and insulating portions.

For these purposes, the sparking plug according to my invention is provided with an insulating member which is adapted to be fitted within the metallic bush in the 1924. Serial No. 729,175.

ignition plug through the end thereof projecting into the combustion chamber in the engine, so that the pressure therein will push the insulating member against its seat in the ignition plug, and assist thereby in assuring tightness. Further, I provide the central portion of the main external metallic body of the plug with openings in its wall, and I considerably reduce in thickness the size of the insulating porcelain so that the latter will absorb a very little amount of heat and transmit same outwardly through its relatively large surface.

The said advantages will be set forth by the following description, reference being had to the annexed drawing forming part of this specification.

In the drawing is shown in axial sectional view a preferred embodiment of my present invention.

The sparking plug according to my invention consists of a substantially cylindrical metallic body l, with an hexagonal, or like, expansion 2 and an externally threaded portion 3 which is adapted to be screwed, as usual, in the thickness ofthe engine wall.

A chamber 4 is provided in the body l, and openings are formed in the wall of said chamber. The upper edge'of the portion 2 is internally threaded to receive a collar-shaped nut 6 adapted to secure the externally conical insulating member 8 of the sparking plug against the circular seat 7 in the portion 2, the space 7l between said seat and the circular shoulder 8l in the insulating member being preferably fitted with a soft packing piece.

The insulating member 8 has formed thereina relatively large cylindrical passage 82 in its upper portion, which projects from the metallic body of the sparking plug, while a larger chamber 83 is provided in the lower portion of said member 8, corresponding to the cylindrical body l of the sparking plug.

The lower portion 3 of the sparking plug is also internally threaded, and the interchangeable elect-rode carrying member is screwed from downwardly therein.

The electrode carrying' member consists of a hollow cylindrical metallic member 16, adapted to be screwed into the portion 3 of the sparking plug. Said hollow member 1.6 is provided at its outer edge with one or more projecting electrodes 17 bent towards its centre, and with a. flange 23 at its inner end. The main electrode 9 extends through the insulating member 8, and projects at the upper end of the latter. The said electrode has its lower end 18 opposite the spike or spikes 17, and is enlarged as at 19. The electrode 9 is threaded as shown, and its lower portion isv tightly surrounded by an insulating` bush 20, which is formed with an inner contraction to provide a seat for the upper shoulder of the enlargement 19, and anv outer contraction 21 adapted to bear against the lower face of the flange 23 in the member 16. rlhe upper portion of the insulating bush 2O is surrounded and covered at its upper end by a barrel-shaped insulating piece 22, the lower edge of which is adapted to bear against the upper face of the said flange l23.

A nut 24 and a lock nut 25 are screwed against the upper face of the barrel 22 to i tighten both said barrel and insulating piece Y surrounded by air 2O against the fiange 23, due to the tension produced by screwing upon the electrode 9.

The barrel 2,2 and nuts 24 and 25 are thus freely surrounded by air entering through the openings 15 and circulating in the chamber 83, so that heat 'conducted by the electrode 9 will diffuse through said air, while tle next upper portion of the said electrode is in the passage y82 and cooled thereby. A washer 10 provided with cross openings 11 allows of the cooling air circulating around the rod 9 and nuts 241, 25, thus facilitating the cooling of these parts,

` Ailocl nut 12 is used to secure again the upper portion of the central rod against the stationary members of the sparking plug, while a washer 13 and a knurled binding screw lil are provided to attach the electric wire thereto. A

It will be seen that the several inner portions are thereby efficiently cooled, that the portion of insulating material projectingchanged when the sparking plug becomes Y damaged, owing to that in such cases the interchangeable ignition plug only has to be changed.

What l claim as my invention is:

A sparking plug of the kind described, comprising a cylindrical hollow body having an internally threaded projection, a metallic bush screwed into said projection, a flange at the innermost end of said bush, a contracted insulating member fitted in said bush against thelower face ofthe flange therein, a Vcylindrical hollow portion of said insulat- .ing member projecting over said liange, a barrel-like insulating member Vsurrounding said cylindrical hollow portion,fmeans being provided to secure together both the internal insulating member and the free edge of the barrel member against the flange in the metallic bush.

In witness whereof, I have hereunto signed my name.

Mrcnnnanenno sacem. 

